The present invention relates generally to the application of non-invasive techniques to the delivery of therapeutic agents. Specifically, the present invention relates to an injection catheter for the treatment of heart diseases or other organs by the injection of therapeutic agents and/or placement of implants.
A number of techniques are available for treating heart disease and diseases of other organs percutaneously. An example of one such technique is percutaneous myocardial revascularization (PMR). This procedure is performed to increase blood perfusion through the myocardium of a patient. For example, in some patients, the number of lesions in coronary vessels is so great, or the location so remote in the patient vasculature, that restoring blood flow to the heart muscle is difficult. Percutaneous myocardial revascularization (PMR) has been developed as an alternative to techniques which are directed at by-passing or removing lesions. PMR is performed by boring holes directly into the myocardium of the heart. Positive results have been demonstrated in some human patients receiving PMR treatments. These results are believed to be caused in part by blood flowing from within a heart chamber through patent holes formed by PMR to the myocardial tissue. Suitable PMR holes have been proposed to be burned by laser, cut by mechanical means, and burned by radio frequency devices. Increased blood flow to the myocardium is also believed to be caused in part by the healing response to wound formation, specifically, the formation of new blood vessels in response to the newly created wound.
What remains to be provided are improvements and devices for enhancing the effectiveness of percutaneous myocardial revascularization. What also remains is the extension of these and other refinements to the treatment of various forms of heart disease and diseases of other organs.
The present invention includes devices and methods for treatment of heart disease and diseases of other organs. The primary focus of the devices and methods of the present invention is the treatment of heart disease, but it should be appreciated that, as explained in more detail below, the devices and methods can be used to treat the diseases of other organs. In some instances, the techniques will vary depending upon the disease being treated.
An exemplary embodiment of the present invention includes, devices and methods for increasing blood circulation to the myocardium. Circulation can be increased through patent holes into the myocardium from a heart chamber and from new blood vessel growth. New blood vessels can provide blood supplied from within a heart chamber, such as the left ventricle, and from pre-existing vessels in nearby healthy heart tissue. New vessel growth can be promoted by the healing response to wounds created in accordance with the present invention. New vessel growth can also be promoted by angiogenic substances supplied to the myocardium in accordance with the present invention.
One set of methods according to the present invention utilizes implants such as tubes implanted into the myocardium, preferably from within the heart, delivered by a catheter. The tubes preferably contain, or are coated with, an angiogenic substance capable of being released over time. These tubes can be biodegradable, being absorbed by the body, some embodiment tubes leaving a patent hole in the myocardium surrounded by the absorbed angiogenic material. Other PMR tubes are not biodegradable, but have lumens therethrough with side holes along the tube length, providing access to the myocardium from with the lumen. The non-biodegradable tube can be formed from a metal, polymer or other bio-stable material. The non-biodegradable tubes are preferably coated with and contain releasable angiogenic material, promoting new vessel growth along the length of the tube, where the new vessels may be supplied with blood through the tube side holes. One method utilizes PMR tubes implanted into the myocardium from outside the heart and can be performed during open heart surgery or during a minimally invasive procedure. In one embodiment, a growth factor may be infused in a slow release polymer. The growth factor or drug and polymer can be placed in a tube having side holes for drug release. By placing the growth factor or drug in the polymer the growth factor or drug can be slowly released into the myocardium after implantation of the tube therein. In one embodiment of the tube containing the growth factor or drug and slow release polymer, the tube includes side holes and sealed ends.
Another set of methods according to the present invention involves injecting angiogenic material into the myocardium. A preferred method includes creating small bore holes or direct needle injection, for example using micro needles, into the myocardium utilizing a catheter within the heart. In the case of hole creation, a fluid, gel, polymer (biodegradable or biostable) or adhesive carrying an angiogenic material is injected into the hole. As the angiogenic substance is absorbed into the myocardium, in one method, a patent hole remains surrounded by myocardial tissue treated with angiogenic material. In another method, the injection hole closes, leaving no patent hole. New vessel growth is promoted by both the healing response to the wound and by the angiogenic substance. Blood circulation to myocardial tissue is increased by both the presence of the patent hole and the presence of new blood vessels supplied by existing coronary vessels and the heart interior. An alternative method utilizes angiogenic material injected into the myocardium from the exterior of the heart, in conjunction with open heart surgery or during a minimally invasive procedure.
In yet another alternate method, angiogenic materials are delivered to the heart to promote new vessel growth. The new vessel growth is the consequence of the presence of angiogenic material, for example, growth factor, and any tissue reaction such as inflammation, rather than wounding of the tissue.
Yet another set of methods includes externally wounding the heart and applying an external patch containing an angiogenic substance to the wound. The wound preferably penetrates into the myocardium. The healing response, enhanced by the angiogenic material, promotes new vessel growth near the wound. While the wound does not normally penetrate through to the heart chamber interior, new vessel formation can reach the chamber interior and also connect with pre-existing vessels in healthy heart muscle. A wound or series of wounds extending from healthy into hibernating tissue can create a network of vessels from healthy into hibernating tissue, supplying the hibernating tissue with blood. In another method, an external patch containing angiogenic material is applied to the heart without significant injury to the heart.
Any therapeutic agent, including small molecular drugs, proteins, genes and cells which could promote angiogenesis, protect tissues (i.e., cardiac protection), or promote tissue regeneration including Vascular Endothelial Growth Factor (VEGF) and Fibroblast Growth Factors (FGFs) is believed to be suitable for use with present invention. Carriers for the therapeutic agents of the present invention include polymers and angiopoietins including biodegradable and biostable hydrogels, and dissoluble polymers. Adhesives suitable for binding the present invention include fibrin glues and cyanoacrylates.
The injection of therapeutic agents and implantation of implants such as tubes for the placement of patches, is believed to have application to the treatment of other forms of heart disease in addition to the context of percutaneous myocardial revascularization. Some of these diseases include, for example, heart failure, myocardial infarction, and cancers, for example of the bladder, liver and kidneys.